Windows Movie Maker- Start/End times of individual clips seem to be messed up.

A certain clip within my set of clips seems to be somehow corrupted. When the entire movie is played, this clip is skipped over, with only a frame showing. In addition, the preview picture that would normally show on the clip itself in the timeline is laid over the previous clips as well, and I can't see the black and white icon that bookends each clip. . When I attempted to use the Trim tool to manually change the start/end time, it not only did not show, but the symptoms were somehow transferred to the next clip. I have no idea how this happened. Please help!